Re: [PATCH][next] drm/amdgpu: remove redundant assignment to pointer 'ring'

[Alex Deucher <alexdeucher@gmail.com>]

On Tue, Jul 23, 2019 at 9:41 AM Colin King <colin.king@canonical.com> wrote:
>
> From: Colin Ian King <colin.king@canonical.com>
>
> The pointer 'ring' is being assigned a value that is never
> read, hence the assignment is redundant and can be removed.
>
> Addresses-Coverity: ("Unused value")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c b/drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c
> index 93b3500e522b..a2a8ca942f34 100644
> --- a/drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/vcn_v1_0.c
> @@ -1331,7 +1331,6 @@ static int vcn_v1_0_pause_dpg_mode(struct amdgpu_device *adev,
>                                 WREG32_SOC15(UVD, 0, mmUVD_JRBC_RB_CNTL,
>                                                         UVD_JRBC_RB_CNTL__RB_RPTR_WR_EN_MASK);
>
> -                               ring = &adev->vcn.inst->ring_dec;
>                                 WREG32_SOC15(UVD, 0, mmUVD_RBC_RB_WPTR,
>                                                    RREG32_SOC15(UVD, 0, mmUVD_SCRATCH2) & 0x7FFFFFFF);
>                                 SOC15_WAIT_ON_RREG(UVD, 0, mmUVD_POWER_STATUS,

While we don't use ring here, I think the assignment is useful to
delineate that we are no longer working with the jpeg ring, but rather
the decode ring.  The mmUVD_RBC_RB_WPTR register is part of the decode
ring, not jpeg.  We would normally use the ring->wptr like we do for
the other rings, but in this particular case, the value happens to be
shadowed to a scratch register due to the way the dynamic power gating
works on that ring.

Alex

> --
> 2.20.1
>
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